Light communication technology using light in a visible light range has recently attracted a lot of attention. Particularly, following rapid progress in the propagation of lighting devices using light-emitting elements including a light-emitting Diode (LED), etc., research and development have been conducted on implementing a very convenient data communication environment (i.e. a visible light communication system) by utilizing a lighting device installed inside or outside of a house. When considering influence on human bodies, medical devices, etc., an LED becomes the strongest candidate among light-emitting elements used in light communication.
However, a data transmission speed in light communication depends on a response speed of a light-emitting element or a driving circuit for the light-emitting element. Therefore, for the purpose of requiring a high data transmission speed, a Laser Diode (LD) or a Super Luminescent Diode (SLD), which has a faster response speed than the LED, is also considered as a strong candidate.
In order to make a data transmission speed more improved, technology for stably transmitting large amounts of data during the emission of a single signal by a light-emitting element is also required. As an example of the light communication technology as described above, the following patent document 1 discloses a technology for eliminating space interference by allocating the time axis of an OFDM (Orthogonal Frequency Division Multiplexing) signal in a space direction.